According to U.S. Pat. No. 4,405,208, organopolysiloxanes containing acryloxy groups are obtained in a hydrosilylation reaction by reaction of organopolysiloxane containing Si-bonded hydrogen with propargyl (meth)acrylate. The propargyl alcohol employed for preparation of the propargyl (meth)acrylate has a relatively high toxicity, and the esterification of propargyl alcohol with (meth)acrylic acid gives poor yields.
The reaction of organopolysiloxane containing Si-bonded hydrogen with beta(allyloxy)ethyl methacrylate in the presence of a hydrosilylation catalyst is known from EP-A 130 731. Organopolysiloxanes containing methacryloxy groups are obtained in this reaction. Organopolysiloxanes containing acryloxy groups are not obtainable selectively by an analogous reaction, since hydrosilylation occurs both on the acrylic and on the allyl radical.
U.S. Pat. No. 5,214,077 describes the reaction of silanes and organopolysiloxanes containing Si-bonded hydrogen with alkynyloxy (meth)acrylates in the presence of a hydrosilylation catalyst. In this reaction, a maximum of one (meth)acrylic group is added on per Si atom.
DD-A 298 404 describes a process for the preparation of siloxanylalkenediyl bis(meth)acrylates. In this process, organopolysiloxane containing Si-bonded hydrogen is reacted with but-2-yne 1,4-dimethacrylate in the presence of a hydrosilylation catalyst. Toxic organic monomers, such as but-2-yne 1,4-dimethacrylate and but-2-yne-1,4-diol, from which the dimethacrylate is obtained by reaction with methacrylic acid, are employed.
It is known from U.S. Pat. No. 4,940,766 that polysiloxanes containing hydroxyalkyl groups can be given corresponding functionalization with (meth)acrylic acid ester groups by transesterification with (meth)acrylic acid alkyl esters under tin catalysis, making it possible for a Si atom to be substituted by a maximum of one functional group.
Siloxanyl-alkenediyl-bis-.omega.-hydroxypolyoxyalkylenes and their use as surfactants are known from DD-A 255 737. DE-A 40 32 006 describes defoamers based on such organopolysiloxanes.